1. Field of the Invention
The present invention relates to printhead skew correction in an electrophotographic machine, and more particularly, to a method of compensating for electronic printhead skew correction in an electrophotographic machine, such as a laser printer, to reduce the occurrence of undesirable print artifacts.
2. Description of the Related Art
In an in-line color electrophotographic imaging process, latent images are formed on a plurality of photosensitive drums, which are in turn developed using a predetermined color of toner. The developed images are then transferred to a sheet of media (such as paper) which travels past the drums. The image in each color is created one line at a time, and the lines are oriented at right angles to the direction of travel of the sheet of media. The individually-generated images combine to form a full-color image. In a typical multi-color laser printer, for example, the sheet of media passes through four color developing stations in series, with the colors being black, magenta, cyan and yellow.
It is recognized that in order for the multi-color laser printer to print accurately, the laser beams for all four colors must be in alignment, both in the scan direction (across the page) and the process direction (feed direction of the print medium). However, providing proper alignment of even a single laser printhead in relation to the sheet of media in the process direction can be difficult. This problem is compounded with the addition of each printhead, since the plurality of printheads must be in registration so that the individual images generated by each printhead can be superimposed correctly when combined. During printer assembly an attempt is made to optically align the laser printheads both individually and collectively, but the ability to provide precise alignment is limited by several factors, including component tolerances. In addition, it is possible for a precisely aligned printing system to drift out of alignment over time due to component aging and ambient environmental factors, such as printing temperature.
What is needed in the art is a method of providing electronic printhead skew correction to compensate for alignment errors remaining after initial printhead alignment, while providing compensation to reduce undesirable print artifacts that can be created by applying the electronic printhead skew correction.